Thread: Is 20 MPG or more possible

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I have a 65 custon 500 (cheap galaxie) that has a 70 302 (500 CFM holley 2 bbl) with a 3 speed manual trans with 3.00 gears,I took it on its first long trip which I put 147 miles on it and used 8.5 gallons of gas which comes out to a little more the 17 which I thought was not too bad but would like to get better. I have a 5 speed from a late 80s mustang and I am planning on installing a 600 CFM 4bbl when I replace the couple noisey lifters so I am thinking the low 20s could be possible with the 5 speed and 3.00 gears. I thought about putting a slightly taller gear in it but the little 302 would have a hard time getting it going so the 3.00 will stay. Even with the 3.00 gears at 70 the 302 sounds like its turning a bit and I do not have stock mufflers so its time for a tach to see how fast the motor is actually turning but overdrive will help a bunch and hopefully not slow the motor too much. Jeff

My '84 Crown Vic has a 302 in it, and one of those factory in dash monitors that tells you the fuel milage, outside temp, etc.

Going down the road at about 55 it will get 26 MPG, at 60 it drops to about 24. It probably weighs more than your '65, but the reason for the better milage is technology. It is fuel injected and computerized, and has an electronic ignition vs points (if yours is still stock) It also has an AOD trans.

The 5 speed should help, as well as a better ignition system, and a really good state of tune, but without the modern induction and computer, it is hard to really get these babies to go over 20.

JMO,


Don

my 66 ford 4 dr custom with factory 289 2bbl dual exaust and 3 spd standard gets really good gas milege close mid 20s
i dont know what my rear gears are but 1900 rpm is about 60 mph .
you should do better with the 5 spd
4t is 1 to 1 like high in the 3 spd
my 3 spd just barly cuts it as the rear gears are too high. 1st is hard on the clutch.
i personaly am not a real believer in the big holley 2 bbls for gas milege.
you should do better with a nice small 4bbl
i know better mpg is possible for ya.

Jeff, I would definitely go with a Rochester Q-jet. You'll get better performance with it than any other 4-bbl. Honest Injun!!

Fuel injection is planned but will be down the road a bit but I will be putting on the 4 bbl soon as that noisey lifter is going to get quieted and I will be going to electronic ignition at the same time with the duraspark system from the local junkyard. Jeff

Originally Posted by techinspector1

Jeff, I would definitely go with a Rochester Q-jet. You'll get better performance with it than any other 4-bbl. Honest Injun!!

Yeah, I wonder why the Quadrajet has gotten such bad press? They actually are, as Tech said, decent carbs. Just about every inboard or inboard/ outboard comes with one, be it Volvo, Mercruiser, etc. We have very little problems with servicing them, and as long as you stay out of the secondaries, they are really economical with those small primaries.

Don

Originally Posted by Itoldyouso

and as long as you stay out of the secondaries,
Don

That's the major problem. If you mess with the secondaries you can get lost in a hurry if you're not really familiar with the adjustments. I'd opt for Holley's Quadrajet replacement.

No, I meant keep your foot out of the secondaries.

Don